Red-luminescent europium (III) doped silica nanoshells: synthesis, characterization, and their interaction with HeLa cells.

A simple method to fabricate Eu(3+) doped silica nanoshells particles with 100 and 200 nm diameters is reported. Amino polystyrene beads were used as templates, and an 8 to 10 nm thick silica gel coating was formed by the sol-gel reaction. After removing the template by calcination, porous dehydrated silica gel nanoshells of uniform size were obtained. The Eu(3+) doped silica nanoshells exhibited a red emission at 615 nm on UV excitation. The porous structure of the silica shell wall was characterized by transmission electron microscopy measurements, while particle size and zeta potentials of the particles suspended in aqueous solution were characterized by dynamic light scattering. Two-photon microscopy was used to image the nanoshells after assimilation by HeLa cancer cells.